As experiment I found some really nasty rusty coins on the street. They were green. After looking on a website I found vinegar could eliminate the rust. It worked pretty well.
I know this is a redox reaction. Can you tell which ones? I know these are pesos of various denominations from Dominican Republic from the past 10 or 20 years. So that might help identify the metal.
The vinegar is household apple cidwe vinegar from the supermarket. Low concentration.